Control system for an impact device

ABSTRACT

A pneumatic ram has its blow intensity varied by varying the time of opening of a valve connecting a constant pressure fluid supply to the cylinder in order to vary the fluid pressure applied to the piston driving the ram. Control means includes timing means to regulate opening of the valve and metering means. Programming is achieved by providing various stations of selected blow intensities and using counting means to count preselected numbers of blows at each selected intensity. Automatic operation depends on means to provide automatic ram return to retracted position.

United States Patent [191 Hague CONTROL SYSTEM FOR AN IMPACT DEVICE [75] Inventor:

Wilmer W. Hague, Fayetteville, Pa.

Assignee: Chambersburg Engineering Company, Chambersburg, Pa.

Oct. 30, 1972 Filed:

Appl. No.:

U.S. Cl 91/40, 9l/l65, 91/248 Int. Cl. FlSb 21/02, FOlb l/OO Field ofSearch 9l/35, 37, 39, 40, 165,

References Cited UNITED STATES PATENTS 4/1961 Fillmore 91/248 6/1965Pinsenchaum 9/1969 Weyer 9/1969 Orhawa et al. 3/1971 June 25, 19743,590,582 7/1971 German ..9l/35 3,613,505 10/1971 Bubula 91/35 PrimaryExaminer-Edgar W. Geoghegan Assistant Examiner-A. M. Zupcic Attorney,Agent, or Firm-Dorfman, Herrell and Skillman [5 7] ABSTRACT 14 Claims, 8Drawing Figures PAIENImJuuzs-mm 50L. CaA/TROL TERMINALS-v5 E dercontaining a piston driving the ram of the impact device. The presentinvention permits not only the timing of a single blow, but theexecution of sequences of blows in a repeatable variable intensityprogram or patpressure of the drive fluidadmitted to the cylinder.

U.S. Pat. No. 3,464,315, the invention of H. A. Weyer, entitledPneumatic Servo Control System for High Speed lmpact Devices assigned tothe assignee of the present invention discloses an impact device havingmechanical controls which produce a blow impelled by the pressure of thedriving fluid admitted to the cylinder. Operation of this impact deviceis automatic, and it will strike repeated blows if its throttle valvemaintains an operating position. Fluid compressed by the piston movingthe raminto impact position is collected in a reservoir as it iscompressed and the energy thus stored is used for returning the ram toretracted position, the retracted position being a constant level fromthe point of impact.

Another U.S. Pat. No. 3,043,271 assigned to the assignee of the presentinvention concerns a control system for an impact device, such as a drophammer, employing variable length strokes to achieve a pattern of blowsof varying intensity as opposed to the present invention wherein blowintensity is regulated by fluid pressure driving the ram. t

Other United States patents, not owned by applicants assignee butconsidered-in connection with the present invention are U.S. Pat. Nos.2,933,068 and 3,133,472. Pat. No. 2,933,068 the invention of A. R.Johnson and Joseph C. Kern concerns a pneumatically operated impactdevice using a mechanically adjustable retainer to hold its piston atthe top of its stroke. Changing retaining force' results in a change instriking pressure'developed and a consequential change in impactintensity. No suggestion of the timing of the pneumatic impact toregulate blow intensity is found.

Pat. No. 3,133,472 does control fluid flow in a impact device usingvalves and regulators to vary impact frequency and impact forceindependently. Impact force is controlled in part by the pressure of thefluid admitted to the striking side of the piston and in part by thetime interval over which fluid is allowed to enter the cylinder. Thetime interval is generated by the pneumatic differential pressure actingwithin the valve. Shifting time of this valve is adjustable and dependson spring rates, diaphragm stiflness and differential areas on whichopposed pneumatic forces act. The teaching of the present invention ofusing timing means to control the opening and closing of a main valve isnot suggested. in the present invention varying inlet time varies ramvelocity.

The present invention constitutes a stroke control particularly usefulfor the impact devices broadly of the type described in Pat. NO.3,464,315, but modified to be useful with the control system of thepresent invention. The control system of the present invention is alsouseful on various impact devices of the same general tern, wherein theintensity is controlled entirely by the class. Characteristically thepresent invention provides means for producing variable intensity blowsby controlling the admission of pressurized fluid, normally air, atprecisely timed intervals to drive the ram. For a fixed supply pressure,ram velocity is determined by the time interval during which pressurizedair is admitted to the cylinder. Additionally, the present inventionpermits for the first time a preset pattern of blows, of the same orvaried intensity, to be set up in advance so that the pattern isprecisely repeatable. The system permits alternative manual operation,if desired, and also permits interruption of the pattern if desired,i.e., the preselected program may be interrupted between selectedimpressions, or groups of impressions, called stations or sequences.Alternatively, the device may continue to strike through one, or anynumber (including all), stations. Stations are defined as a continuoussequence of blows of the same preselected intensity.

More particularly, the present invention relates to a stroke controlsystem for an impact device having a frame supporting at least onecylinder. A piston within that cylinder is connected by suitable meansto a ram such that the ram is movable relative to the frame from aretracted position into impact position. A fluid supply system includesa driving fluid supply and valve means for admitting compressible fluidfrom said driving fluid supply to said at least one cylinder at aposition in the cylinder to drive said ram into impact position. Thecontrol system includes operating means for opening and closing thevalve means, including timing means for determining the period of timethe valve means will remain open. Pressure regulating means formaintaining the fluid pressure in the fluid supply essentially constantis also provided, as is metering means in the supply system, such thatflow of fluid for selected increments of time permitted by the timingmeans will determine the pressure in said cylinder in order to drive theram at a different predetermined force for each selected time increment.Inherent in this system is the metering effect which prevents immediatetransfer to the piston of pressure from the fixed regulated drivingpressure supply. The metering causes a gradual transfer of fluid so thatthe pressure which enters the cylinder to drive the piston willgradually build up. Thus it is possible to control the actual drivingpressure on the piston by timing the period a valve controlling flowthrough the metering means is open.

Preferably means is provided such as reservoir means in communicationwith the cylinder at such location that fluid compressed in the cylinderand reservoir means by the piston moving the ram into impact positionprovides stored energy to retract the ram when the fluid pressure islater exhausted from the other side of the piston.

Preferably the timing means is adjustable in order to provide blows ofdifferent predetermined energy corresponding to selected timeincrements. Furthermore, the timing means is preferably provided withdiscrete incremental positions in order to provide blows of selectedrepeatable blow intensities.

in order to provide a programmer, at least one counting means isprovided to count a predetermined number of blows at selected blowintensity and sequencing means is provided to cause said at least onetiming means to control the period of valve opening for differingpredetermined times in a predetermined sequence. Stop means may beprovided which interrupts the program at any time, or stop means may beprovided to selectively interrupt a program at a predetermined point,permitting continuation of the program thereafter.

For a better understanding of the present invention, reference may behad to the accompanying drawings in which FIG. 1 is a diagram of animpact device and control console, showing valve means for admittingcompressible fluid in position to admit fluid under pressure to drivethe ram from retracted position shown to impact position;

FIG. 2 is a similar diagram showing the same impact device with itsvalve means in alternate position permitting exhaust of the cylinder andallowing the ram to be returned from impact to retracted position;

FIG. 2a is an enlarged sectional view of the main valve showing it inretracted exhaust position;

FIG. 3 is an enlarged front elevational view of the front panel of thecontrol console;

FIG. 4 is an energy calibration chart wherein blow intensity as apercentage of rated size is plotted against blow intensity settingscorresponding to time intervals for various constant drive fluidpressures;

FIG. 5 is a schematic circuit diagram partially in block form showingthe alternating current portion of a preferred control circuit; and

FlGS. 6a and 6b together form a circuit diagram of the direct currentportion of a preferred control circuit.

Referring to FIGS. 1, 2 and 3 there is shown a pneumatic impact devicewhich, in its preferred form constitutes a high speed sequence programcontrolled die forger with suitable controls. The device depicted ishighly schematic in that the hammer itself is to a large degree of thesame general construction as that hammer shown in US. Pat. No.3,464,315, to which reference may be had for further details ofconstruction. FIG. 1 depicts the preferred embodiment of the presentinvention schematically with its ram in retracted position. FIG. 2depicts the same hammer with its ram in impact position.

The device shown is a high speed forging hammer for flat die work andimpression die work controlled by an electrical sequence programcontrolled system as opposed to the mechanical pneumatic servo controlsystem of the aforesaid patent, which accounts for a number ofdifferences in the control feature.

Like the earlier device the major parts of the hammer are the anvil 10,a pair of upright frame members 12 and a yoke 14. These parts are boltedtogether in conventional fashion for a machine of this type toaccomodate heavy impact vibration forces. The anvil and frame membersare generally standard cast construction but the yoke is modified and ofthe general type taught by Pat. No. 3,464,315. The yoke 14 is providedwith various cavities, the largest of which is centrally locatedcylinder 16, which is of generally right circular cylindrical form witha vertically oriented axis. In this cylinder is located a piston 18,which is moved up and down within the cylinder by introduction of airunder pressure. Air is introduced and removed from the cylinder throughports in its walls. The piston 18 is connected by piston rod 20 to a ram22. The piston rod passes through suitably gasketed bushings to preventleakage of air from the cylinder along the piston rod.

The ram is always in contact or close proximity with and guided by guidepieces 24 which are bolted onto the frame members 12, four of whichguide pieces are preferably used in order to assume the same rampositioning at impact, blow after blow. The anvil 10 and the ram 22,respectively, carry forging dies 26a and 26b between which is fed metalstock to be forged in conventional manner. The piston 18 is providedwith suitable piston rings which effectively prevent flow around theedges of the piston between it and the cylinder walls. The cylinderpreferably has a replaceable cylinder liner providing a uniform cylinderwall and wear surface for cooperation with piston 18. The top of thecylinder is closed by a suitable cylinder head 28, preferably bolted tothe yoke 14. A reservoir or surge tank 30 communicates with the cylinder16 through passage 32 at the bottom of cylinder 16. Air under pressureis fed into the reservoir 30 through suitable feed means (not shown)provided with pressure regulating means which is arranged to admit aironly when pressure drops below a predetermined value. When greater airpressure is applied to the impact (upper) side of piston 18 to urge thepiston downward driving the ram 22 to impact, air is forced out of thebottom of the cylinder through passage 32 into reservoir 30 and in thisprocess the total volume of air is compressed. Then when air isexhausted from the cylinder above the piston the pressure of the air inthis reservoir 30 drives the piston back upwardly. Ordinarily the pistonis retained in its retracted position shown in FIG. 1 solely by thepressure of air beneath the piston and in reservoir 30. This pressure issufficient without other mechanical restraint to hold the ram ready foruse until driving air is reintroduced above the piston.

The present invention provides a constant fluid pressure supply 34,which is used directly to supply pressure to pilot valves and which isregulated to the selected pressure for use by the main cylinder by anadjustable pressure regulator 36. Regulator 36 permits a change in theconstant pressure supplied by fluid pressure supply 34 to the inlet duct38. Located in the inlet duct is a trip valve 40. Ordinarily in thecourse of operation the trip valve 40 is initially mechanically openedto make the system ready to operate. However, a solenoid actuator 46responds to an emergency pushbutton to close the trip valve to shut offfluid pressure supply, exhaust downstream pressure and stop or retardthe progress of the ram toward impact. At the end of the inlet duct 38is the main valve 42. The main valve has three positions. In the openposition shown in FIG. 1 the valve spool 41 is held by pilot air againstspring pressure in its lower position so that the air from duct 38communicates directly with the cylinder 16 above the piston 18 throughduct 37. In its closed position shown in FIG. 2 the spool 41 has beenmoved up by spring pressure so that the inlet is shut off from duct 37,and the cylinder 16 through duct 37 communicates with exhaust duct 44.The main valve 42 is operated into open position shown in FIG. 1 by asolenoid 50 operating a pilot valve 48 in the pilot supply line directlyfrom fluid pressure supply 34.

It should be understood that somewhere between the regulator 36 and thecylinder 16 above piston 18 is located appropriate metering means whichprevents immediate transfer to the piston of the full regulatedpressure. Metering can be provided by the size of the inlet duct 38, bylimiting the size of opening of main valve 42 or even by introducing ametering orifice into the system. ln a manner to be described hereafter,by timing the period the trip valve 40 is open the pressure applied tothe piston can be selected and controlled within narrow limits.

FIG. 2a shows the main valve 42 in a special expansion position achievedby applying pilot pressure to and cup-shaped valve member 43 to raise itinto the position shown against spring pressure. Pilot valve 52 whenpositioned by energization of solenoid 54 connects fluid pressure supplyto the expansion valve 43 which moves to the position shown in FIG. 2ato impede the flow of air out of the cylinder 16 in a situation such asthe last blow of a series where fluid pressure may not be fed into thecylinder 16 above the piston, to cushion its upward motion. Theexpansion valve 43 may also be used to allow air to expand in thecylinder to conserve compressed air. Solenoids 50 and 54 and their pilotvalves 48 and 52 for operating main valve 42 are preferably shockmounted atop the crown of the machine.

below the duct 37 of the main valve 42. As shown in FIG. 2, when the dieforger is operating the safety plunger 56 is withdrawn by solenoid 58.

In the position of the ram 22 during its upward rise a position-sensingswitch 60 is provided at a predetermined position along the upward pathof travel of the ram to be actuated by the ram at that point. The switch60 may be adjustably positioned along its support rod by which it isattached to the frame 12. The switch 60 is used to initiate the returnof the main valve to open position to allow fluid to flow from the fluidsupply 34 into the cylinder 16. As will appear hereafter this switchalso initiates a timing relay which determines howlong the valve 42remains inopen condition and thus determines the intensity of theimpact.

The operation of the machine as described is initiated by use of a foottreadle 64 which provides a switch which may be operated at the will ofthe operator to manually actuate the ram when it is set for manualactuation, or to interrupt and reinitiate.

Also shown in FIG. 1 is a control console generally designated 66 whichcontains the electrical circuitry for operating the die forger in apreprogrammed sequence of blows in a fashion determined by the manualselection means occupying the panel, generally designated 68, which isshown in greater detail in FIG. 3.

Before giving detailed consideration to the selection and indicatormeans shown in FIG. 3 it is desirable to understand the capabilities ofthe control means contained within the control cabinet 66. The controlmeans of the present invention enable an operator to select blowintensity of the ram in a particular die forging operation by timing theperiod during which the main valve 42 is open to the fluid supply. Sincethe flow from the fluid supply to the cylinder 16 is restricted andrequires a finite time to reach the full pressure of the fluid supply,the longer the valve is open to a certain point the greater will bepressure supplied cylinder 16 above the piston 18 for a given fluidsupply pressure. For the sake of repeatability and reliability ofsetting, discreet increments of time are provided corresponding toincreasing blow intensity settings for increasing time the trip valve 40is allowed to remain open.

FIG. 4 illustrates the effect of varying the blow intensity setting fora given supply pressure where the blow intensity is expressed as apercentage of rated size. In passing it should be noted that this chartassumes a fixed lifting air pressure beneath the piston, since avariation in that pressure will also cause a variation in the effectillustrated in the chart of FIG. 4. Ordinarily, however, lifting airpressure supplied beneath the piston 18 is kept at a constantpredetermined amount which may be observed on a lifting air pressuregauge 70 on console 66. This pressure is kept constant by a liftingpressure regulator. If desired, lifting pressure may be modified by knob72. Similarly the driving or striking air pressure is shown on a gauge74. Again the air pressure is regulated to maintain it constant at afixed setting, but the regulated pressure may be changed by anadjustment knob 76.

In addition to the selection of force of blow through adjustment of thetiming in accordance with the present invention, it is also possible toselect the number of blows at the given blow intensity, the number ofblows selected for a given intensity being known as a station of thecontrol program. In accordance with the present invention it is possibleto have multiple stations in each of which is provided a selectablenumber of blows of selected intensity. In the control panel shown inFIG. 3 provision has been made for five stations. Controls for thevarious stations are designated by the numerals to the left of the rowsin their sequence of operation. The first column 78 provides indicatorlights 78-], 78-2, 78-3, 78-4 and 78-5, only one of which will beilluminated at a time to designate which particular station is inprogress. The second column 80 contains selector switch dials 80-1,80-2, 80-3, 80-4 and 80-5, by which in this particular embodiment, aselection of up to fifteen sequential blows of the same intensity may bemade for each station. The third column 82 contains selector switchdials 82-1, 82-2, 82-3, 82-4 and 82-5 having ten positions providing tendiscreet preselected intensities of blow determined by the timing periodof the associated timer means in each case. The final column 84 containsrestart/continue selector switches 84-1, 84-2, 84-3 and 84-4 whichpermit a choice between stopping at the end of the selected number ofblows of each station or automatically continuing on to the blows of thenext station. Not all of the stations, or sequences, need to be used.The number of stations employed in a particular process is selected bythe sequence selector switch 86. As the blows actually take place, theblows of the currently active station are counted by a binary counterand displayed by a binary blow count indicator 88, consisting of fourlights representing from left to right I, 2, 4, and 8 blows, which areadded to determine the equivalent number of blows in decimal units.

The panel also provides for a blow set control 90, a no-blow safetyswitch 92, both of which function as safety control. The blow setcontrol must be pressed before the ram can be initiated. In the event ofemergency the no-blow safety switch is pressed to interrupt theoperation at any point. Overall operation may be manual, simply usingthe foot switch 64, or automatic, using the program set up by thecontrol panel 68, according to which one of two positions is assumed bythe manual-automatic selector switch 94. If desired, an automaticlubricator system may be provided and an indicator light 96 on the panelwill show when it is functioning.

Referring now to FIGS. 5, 6a and 6b, there is shown in highly schematicform the control circuitry for the control programmer of the presentinvention. FIG. shows a step-down power transformer 98 connecting a 60cycle power source to the control circuit such that the control circuitis provided with l volt, 3 amp. service across the lines 100, 102. Inthis circuit the blow set switch 90 is normally open and when it closesit connects the blow set relay BSR across the 1 15 volt power linesthrough the no-blow safety switch 92, which is normally closed and canbe opened at any time, in case of emergency, to disrupt the operation ofthe control circuit. The function of the blow set relay functions toclose the normally open contacts BSR-l in series with the trip valvesolenoid 46 across the power lines to thereby energize the trip valvesolenoid, opening trip valve 40 as previously described. The relay BSRprovides normally open contacts BSR-2 in the power line 100 so that,until the blow set switch 90 is closed, power is not supplied across thetransformer/rectifier 104 which produces 24 volt dc for operation of thecontrol function circuitry shown in FIGS. 6a and 6b. The closing ofcontacts BS R-2 also places power across the foot switch indicator lamp106 through normally closed relay contacts FSR-Z of the foot switchrelay and normally closed contacts 2P1, 3P1, 4P1, SP1 and normallyclosed contacts 1PS-]. At the same time the sequence l indicator lamp78-1 is illuminated indicating that the first sequence is set up tobegin. The foot switch 64 when closed energizes foot switch relay FSRwhich closes normally open contacts FRS-l to energize safety plungerrelease solenoid 58 to withdraw the safety plunger 56.

Inlet timer 107 and exhaust timer 108 are both enabled across the powerlines 100 and 102. The exhaust timer 108 is normally a single timerwhich, once set, retains its setting but is normally deterred untilcontacts of the last blow relay close to enable it to function duringthe last blow of a sequence. Its function is to energize the solenoid 54for a predetermined time to impede the flow of exhaust air through valve52 in order to retard the return of the ram on the last blow of asequence of on other occasions when it is probable that the return ofthe piston 18 will not be opposed by new fluid entering the cylinder.The exhaust timer can also be used, if desired, to control expansion ofair in the main cylinder.

The inlet timer usually performs a far more complicated function. Incertain embodiments the inlet timer may, in fact, be a plurality oftimers, one for each sequence, or station. In the present embodiment theinlet timer is preferably a single timer, with multiple settings.Variable resistances, one for each of the respective stations orsequences, are successively switched into a timing circuit with a fixedcapacitance, to provide the needed timing represented by the respectiveRC circuits for each of the sequences. The resistances are adjustable byconventional potentiometer means, but are preferably provided withdetents to give discreet repeatable settings for the selector dials ofcolumn 82 representing blow intensity. Other means of providing thedesired timing will occur to the man skilled in the art in view of theadvanced stage of the timer art.

The sub-circuit of FIGS. 60 and 6b, provides 24 volts dc across thepower lines 110 and 112 from the transformer/rectifier 104 of FIG. 5.The manual automatic selector switch 94 is left open as shown for manualoperation and closed for automatic operation of the program controller.Closing switch 94 actuates automatic control relay ACR.

The normally open contacts FSR-3 of foot switch relay are closed byaction of the foot switch 64, initiating operation and energization ofstart sequence relay SSR, to energize relays 1P and IP. Energization ofrelay SSR also closes contact SSR-1 and another contact of relay SSR toinitiate a cycle reset timer 3TR (not shown) which, like timers 107 and108, is placed across the power lines 100, 102. Energization of a relayACR opens contacts ACR-l to permit sequencing of subsequent relays,which cannot occur during manual operation when contacts ACR-1 remainclosed. Contacts ACR-2 and ACR-3 close to complete an altemate path torelays IP and 1? through normally closed switch contacts of relays ESRand LBR and through contacts 3TR-l and SSR-l. Relay 1? provides normallyopen contacts lP-l which close to energize the first sequence light78-1. Relay 1P enables the restart or continue selector 84-1 and alsosets up the trigger and timing circuit for the first station of inlettimer 107 in the manner previously described. Relay 1P through contactslP'-3 sets up the number selected by the number of sequences selector86. Relay 1P also sets up through contacts lP'-4 (FIG. 6b) the number ofblows selector 80-1, readies relay lPS for the end of the first sequencethrough contacts lP'-2, (FIG. 6a) and enables the second sequence oflight 78-2 through contacts lP-5 (FIG. 5). However, the second sequencelight is held off by other contacts until the last blow of the series.

Relay 1? also triggers inlet timer 107. It will be ap preciated thatwhen the inlet solenoid 50 triggers the main valve 42 by feeding pilotair to the main valve to open the fluid supply to the top of the maincylinder 16, fluid from supply 34 immediately begins to feed into thecylinder. The amount of pressure and the amount of force imparted to theram is proportional to the time thatvalve 42 is open, in the positionshown in FIG. 1. When the inlet timer 107 times out, it functions todrop out the inlet solenoid 50 and pilot valve 48 at which point themain valve 42 closes off the cylinder 16 from the inlet supply and opensthe cylinder to the exhaust duct 44, the ram inertia and pressurecontinuing through this advanced period of ram travel to drive the ramtoward impact. As the ram rebounds air is flowing out the exhaust of thecylinder and compressed air beneath the piston 18 and in the reservoir30 forces the ram to rise.

When the ram rises, if more than one blow is called for by selectorswitch 80-1, the timer 107 is again triggered by the rising ram throughswitch 60 causing a repetition of the sequence described. That is, themain valve 42 is opened to fluid pressure supply 34 through regulator 36for a period determined by blow intensity selector 82-1. The time duringwhich the valve is open will be the same for each blow of the firststation or sequence. On repeated blows the timer is triggered again andagain. In practice the timer 107 pulls in other relays such as one whichserves a number of auxiliary functions including pulsing the relay whichdrives the blow counting counter-circuit 114. Each count is indicated atbinary indicator 88. The respective l, 2, 4 and 8 outputs of the binarycounter, which may be composed of flip-flops, when turned on, alsoactivate control relays lCR, ZCR, 4CR and 8CR. Those relays lCR, 2CR,4CR and 8CR, energized by the counter, close contacts designated bytheir relay number in the blow selector circuit shown in FIG. 6b, in apattern which represents the count. When a coincidence of the blowselector setting and the count indicated by an appropriate combinationof closed contacts of control relay lCR, 2CR, 4CR and 8CR occurs, thecircuit provides a continuous path to energize the last blow relay LBR.In the restart condition LBR is ordinarily maintained by the foot switchcontacts through relay SSR contacts SSR-2 and the restart contacts andcontacts lP-2 of relay 1P (or the corresponding contacts for latersequences).

Actuation of last blow relay LBR or the release of the relay SSRtriggers the exhaust timer 108. Exhaust timer 108 energizes exhaustsolenoid 54 when a last blow occurs as was previously explained. Thensolenoid 54 acts on valve 52 to partially occlude the exhaust duct 44,thereby cushioning the upward travel of the ram. Last blow relay LBR,through nonnally open contacts LBR- l, energizes relay lPS todiscontinue the first sequence. Before timing can be completed thesequence of the next station must be started by reactuating the footswitch 64 to energize relay SSR. Another timing relay initiated by thefoot switch (and by relay SSR) may be provided to prevent work frombeing forged after cooling too much by timing out a time within which adecision about continuing or restarting the sequence must be made whenthe selector 84-1 is put in restart position.

If the selector 84-1 is in the continue position another timer (notshown) reduces the normal time required by exhaust timer 108 to hold themain valve in the exhaust position and allows the next sequence toproceed immediately. In the continue position of switch 84-1 the lastblow relay is maintained by contacts of exhaust timer 108.

As seen in FIG. 6b, all restart-continue switches 84-1, 84-2, 84-3, and84-4 are shown in the restart" position. ln this position the operatormust interrupt the contact of the foot switch (and FSR) in order topermit the sequence of the next station to continue. In the continueposition which closes another set of contacts through a timer (notshown) as long as the operator maintains the foot switch closed, therewill be no interruption in operation between stations. In the restartposition shown, when the respective relay contacts such as lP-2 areclosed by energization of their respective relays and, through relaycontacts SSR-2, a holding circuit is set up for the last blow relaythrough contacts LBR-l.

After the first sequence is completed, normally open contacts lP'-2remain closed so that, upon closing of the contact LBR-l, relay lPS isenergized closing contacts lPS-l for holding purposes, and IFS-2 isclosed to energize relays 2P and 2P through the normally closed contacts2PS-l and 3PS-l. Upon energization of relay 2P, contacts 2P-2 act asholding contacts to keep the relays energized.

As can be seen from FIG. 6a, the circuit of station 2 is like that ofstation 1 and its sequence of operation is essentially the same. Thesame thing is true of stations 3 and 4, which are therefore shown inblock form, it being understood that the pattern of contacts and relaysis the same. Station requires only one relay 5?, since there is no needto set up additional relays. Where relay contacts have not beendescribed the relay is indicated without numbering the contacts so thatcircuit operation can be determined by inspection of relay circuits todetermine when each relay will be effective.

The system has been described omitting details and alternativepossibilities which can be provided as options with the system of thepresent invention. The means to accomplish the results described andmodification of these results are well within the skill of the art andwill be obvious to the man skilled in the art, so that he can readilymodify the controls to perform many varieties of function and the samefunctions in a variety of different ways. All such variations andmodifications within the scope of the claims are intended to be withinthe scope and spirit of the present invention. Description of thespecific embodiment is intended by way of example of a preferredembodiment and is not intended by way of limitation.

I claim: 1. A stroke control system for an impact device having a framesupporting at least one cylinder, a piston within said cylinder andmeans connecting said piston to a ram such that said ram is movablerelative to said frame from a retracted position into impact positionand a driving fluid system, including a driving fluid supply and valvemeans for admitting compressible fluid from said driving fluid supply tosaid at least one cylinder at a position in the cylinder to drive saidram into impact position, comprising operating means for opening andclosing said valve means including timing means for determining theperiod of time the valve means will remain open,

pressure regulating means for maintaining essentially constant the fluidpressure in said driving fluid supply, and

metering means in the supply system such that flow of fluid for selectedincrements of time permitted by the timing means will determine thepressure in said cylinder in order to drive the ram at a differentpredetermined force for each selected time increment.

2. The stroke control system of claim 1 in which exhaust means isprovided to exhaust driving fluid from the impact side of the pistondriving the ram into impact position and lift means is provided toretract the ram after each impact following exhaust.

3. The stroke control system of claim 2 in which the lift means includesreservoir means in communication with said cylinder at such locationthat fluid is compressed by the piston moving the ram into impactposition whereby, following exhaust of driving fluid, compressed fluidin the cylinder and reservoir means provides force to retract the ram.

4. The stroke control system of claim 1 in which means is provided toadjust the driving fluid supply pressure and to regulate it.

5. The stroke control of claim 1 in which said timing means isadjustable in order to time valve openings to provide blows of differentpredetermined force corresponding to selected time increments.

6. The stroke control system of claim 5 in which the timing means has apredetermined number of selectable discreet incremental positions, eachposition corresponding to a predetermined blow intensity.

7. A stroke programmer control system employing the control system ofclaim 6 in which counting means is provided to count a preselectednumber of blows at a selected intensity and to cause the controlfunction to be repeated to repeat the operating cycle for thepreselected number of blows.

8. The stroke programmer control system of claim 7 in which thepreselected number of blows at a selected intensity may be preselectedby adjustment of an ad justable counter means.

9. The stroke programmer control system of claim 7 in which the systemis provided with means for automatically sensing the return of thehammer to retracted position.

10. The stroke programmer control system of claim 7 in which the systemis provided with means for automatically sensing the return of thehammer to retracted position and the preselected number of blows at aselected intensity may be preselected by adjustment of an adjustablecounter means.

11. The stroke programmer control system of claim 10 in which aplurality of adjustable timing means are provided, each with selectablepredesignated timing positions to permit blows of predeterminedintensity, and sequencing means is provided to cause said timing meansto be effective in predetermined sequence.

12. The stroke programmer control system of claim 11 in which eachadjustable timing means is provided with a separate counter permittingmultiple blows of the same intensity determined by each such countingmeans before the sequencing means is effective to select another timingmeans.

13. The stroke programmer control system of claim 12 in which stop meansis provided to interrupt the system manually at any time.

14. The stroke programmer control system of claim 13 in which variousselectable stop means are provided to permit automatically stopping asequence at a predetermined time and means is provided to reinitiate thesequence when desired.

UNHED snares PATENT @FHQE QEE'HHQATE e5 @QERREEFTWN Patent No. 3, 81 799Dated June 25 1974 Inventor(s) Wilmer W. Hague Sheet 1 Of 2 It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

i 1 Correct F180 6a as lam.

may;

Sheet 2 of 2 UNITED STATES PATENT OFFICE 1, CERTIFICATE OF CORRECTIONPatent 3 818 799 Dated June 25 1974 Inventor(s) Wilmer W. Hague It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below;

Column 1, line 55 "pressure" should be pressures 0 Column 5 line 63,Column 6, line 38, column 7,

line 60 and column 10, line 62 change "discreet" to -discrete--.

Column 7, line 31 "FRS-l" should be -FSRl- Signed and Sealed thistwenty-seventh D a) Of April 1976 [SEAL] Atiesr:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmissinner uj'larvnlsand Trademarks UNHED snares PATENT @FHQE QEE'HHQATE e5 @QERREEFTWNPatent No. 3, 81 799 Dated June 25 1974 Inventor(s) Wilmer W. HagueSheet 1 Of 2 It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

i 1 Correct F180 6a as lam.

may;

Sheet 2 of 2 UNITED STATES PATENT OFFICE 1, CETIFICATE OF CORRECTIONPatent 3 818 799 Dated June 25 1974 Inventor(s) Wilmer W. Hague It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below;

Column 1, line 55 "pressure" should be pressures 0 Column 5 line 63,Column 6, line 38, column 7,

line 60 and column 10, line 62 change "discreet" to -discrete--.

Column 7, line 31 "FRS-l" should be -FSRl- Signed and Sealed thistwenty-seventh D a) Of April 1976 [SEAL] Atiesr:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmissinner uj'larvnlsand Trademarks

1. A stroke control system for an impact device having a framesupporting at least one cylinder, a piston within said cylinder andmeans connecting said piston to a ram such that said ram is movablerelative to said frame from a retracted position into impact positionand a driving fluid system, including a driving fluid supply and valvemeans for admitting compressible fluid from said driving fluid supply tosaid at least one cylinder at a position in the cylinder to drive saidram into impact position, comprising operating means for opening andclosing said valve means including timing means for determining theperiod of time the valve means will remain open, pressure regulatingmeans for maintaining essentially constant the fluid pressure in saiddriving fluid supply, and metering means in the supply system such thatflow of fluid for selected increments of time permitted by the timingmeans will determine the pressure in said cylinder in order to drive theram at a different predetermined force for each selected time increment.2. The stroke control system of claim 1 in which exhaust means isprovided to exhaust driving fluid from the impact side of the pistondriving the ram into impact position and lift means is provided toretract the ram after each impact following exhaust.
 3. The strokecontrol system of claim 2 in which the lift means includes reservoirmeans in communication with said cylinder at such location that fluid iscompressed by the piston moving the ram into impact position whereby,following exhaust of driving fluid, compressed fluid in the cylinder andreservoir means provides force to retract the ram.
 4. The stroke controlsystem of claim 1 in which means is provided to adjust the driving fluidsupply pressure and to regulate it.
 5. The stroKe control of claim 1 inwhich said timing means is adjustable in order to time valve openings toprovide blows of different predetermined force corresponding to selectedtime increments.
 6. The stroke control system of claim 5 in which thetiming means has a predetermined number of selectable discreetincremental positions, each position corresponding to a predeterminedblow intensity.
 7. A stroke programmer control system employing thecontrol system of claim 6 in which counting means is provided to count apreselected number of blows at a selected intensity and to cause thecontrol function to be repeated to repeat the operating cycle for thepreselected number of blows.
 8. The stroke programmer control system ofclaim 7 in which the preselected number of blows at a selected intensitymay be preselected by adjustment of an adjustable counter means.
 9. Thestroke programmer control system of claim 7 in which the system isprovided with means for automatically sensing the return of the hammerto retracted position.
 10. The stroke programmer control system of claim7 in which the system is provided with means for automatically sensingthe return of the hammer to retracted position and the preselectednumber of blows at a selected intensity may be preselected by adjustmentof an adjustable counter means.
 11. The stroke programmer control systemof claim 10 in which a plurality of adjustable timing means areprovided, each with selectable predesignated timing positions to permitblows of predetermined intensity, and sequencing means is provided tocause said timing means to be effective in predetermined sequence. 12.The stroke programmer control system of claim 11 in which eachadjustable timing means is provided with a separate counter permittingmultiple blows of the same intensity determined by each such countingmeans before the sequencing means is effective to select another timingmeans.
 13. The stroke programmer control system of claim 12 in whichstop means is provided to interrupt the system manually at any time. 14.The stroke programmer control system of claim 13 in which variousselectable stop means are provided to permit automatically stopping asequence at a predetermined time and means is provided to reinitiate thesequence when desired.